A printing apparatus comprising a light-emitting element, a light-receiving element configured to output a monitor current based on a light-emitting amount from the light-emitting element, a comparison unit connected to the light-receiving element and configured to compare the monitor current with a reference current, a driving unit configured to drive the light-emitting element based on the comparison result, a current generation unit configured to generate a first current, and a conversion unit arranged in a path between the current generation unit and the comparison unit, the conversion unit outputting, upon receiving a control signal, the reference current based on the control signal and the first current.